McCain said Paul's argument that the administration might use a drone to kill an outspoken opponent — someone like Jane Fonda during the Vietnam War — was "ridiculous.”

“To infer that the president is going to kill someone like Jane Fonda or someone who disagrees with him is simply ridiculous,” McCain said on the Senate floor. “If someone is an enemy combatant, that enemy combatant has nowhere to hide, not even in a café.”

“To infer that our government would drop a Hellfire missile on Jane Fonda brings the conversation to a ridiculous tone.”

“Is objection to the policy of your government sympathizing with the enemy?” Paul said. “Are you just going to drop a Hellfire missile on Jane Fonda?” referring to the actress’s prominent anti-war stance during the Vietnam conflict.

Paul has demanded that President Obama say whether he believes he has the authority to launch a drone strike against someone on American soil, and wants the confirmation of CIA nominee John Brennan delayed until he gets an answer.

“I will speak today until the president says, ‘no,’ he will not kill you at a café,” Paul said at the start of Wednesday’s filibuster.

Graham dismissed that scenario as outlandish.

“This president is not going to use a drone against an innocent person sitting at a café because it would be illegal,” Graham said Thursday. “It would be murder.”

In response to the filibuster, the Obama administration on Thursday ruled out a drone attack against a citizen not engaged in combat on U.S. soil.

“The president has not and would not use drone strikes against American citizens on American soil,” White House press secretary Jay Carney said.

Several other Republican senators joined Paul in his filibuster and supported his line of questioning. Graham questioned why members of his party suddenly have problems with the armed drone program.

“I don’t remember any of you fellow Republicans coming down here and saying President [George W.] Bush was going to kill anyone with a drone,” Graham said. “But we had a drone program back then ... so what is it that’s got you so spun up now?”

Paul defended his filibuster in the face of the criticism from Graham and McCain, arguing that he was raising “legitimate questions.”

“What we’ve asked the president is, can you target Americans not involved in combat? It’s a pretty important question,” Paul said Thursday. “Their point is that we haven’t done it yet. That’s the president’s point: 'We haven’t done it yet, we don’t intend to do it, but we might.' I think the answer should be a resounding 'no.' ”

McCain and Graham said it is important for lawmakers to ask questions about the president’s drone program, but accused Paul of inciting fear into Americans by making the “offensive” suggestion that the president could assassinate them.

The GOP senators who joined Paul’s filibuster should “know better,” according to McCain.

"All I can say is I don’t think that what happened yesterday was helpful for the American people," McCain said.

“They’re trying to stand up for the concept of a senator having a questioned answered,” Graham told reporters when he left the floor. “I’ve got no problem with that. I don’t think they’re supporting the policy.”